British Airways is to resume direct flights from London to Tehran, the latest sign of Iran's closer ties with Western countries since the implementation of its nuclear deal with world powers.

The flagship British carrier's first direct flight to Tehran in nearly four years was scheduled to leave London's Heathrow Airport on the evening of September 1 and arrive in Tehran on the morning of September 2.

The flight service was suspended in October 2012 as relations between Iran and the West were deteriorating over Iran's controversial nuclear program.

British Airways plans six roundtrip flights per week with more flights scheduled to be added later in 2016.

British officials have urged companies to seek investment opportunities in Iran following the lifting of some sanctions against Iran under the nuclear deal.